<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <title>1.原生事件</title>
  </head>
  <body>
    <button id="btn">点我</button>

    <script type="text/javascript" >
      const btn = document.getElementById('btn')
      btn.onclick = (event)=>{
        console.log(event)
        alert(1)
      }
    </script>
  </body>
</html>